scholarly journals Observation of the Reversible Ice III to Ice IX Phase Transition by Using Ammonium Fluoride as Anti-Ice II Agent

2020 ◽  
Author(s):  
Christoph Salzmann ◽  
Zainab Sharif ◽  
Ben Slater ◽  
Craig L. Bull ◽  
Martin Hart
Keyword(s):  
Phase Transition ◽  
Thermal Expansion ◽  
Negative Thermal Expansion ◽  
Ammonium Fluoride ◽  
Torsional Strain ◽  
Lattice Constants ◽  
Helical Springs ◽  
Residual Hydrogen ◽  
Fluoride Doping ◽  
The Stability

Ice III is a hydrogen-disordered phase of ice that is stable between about 0.2 and 0.35 GPa. Upon cooling, it transforms to its hydrogen-ordered counterpart ice IX within the stability region of ice II. Because of this metastability, detailed studies of the ice III to ice IX phase transition have so far not been carried out. Using ammonium fluoride doping to prevent the formation of ice II, we now present a detailed study on this phase transition using in-situ powder neutron diffraction. The <i>a</i> and <i>c</i> lattice constants are found to expand and contract, respectively, upon hydrogen ordering yielding an overall negative volume change. Interestingly, the anisotropy in the lattice constants persists when ice IX is fully formed and negative thermal expansion is observed. Analogous to the isostructural keatite and <i>b</i>-spodumenes, the negative thermal expansion can be explained through the build-up of torsional strain within in the <i>a</i>-<i>b</i> plane as the helical ‘springs’ within the structure expand upon heating. The reversibility of the phase transition was demonstrated for the first time upon heating. The ammonium fluoride doping induces additional residual hydrogen disorder in ice IX and is suggested to be a chemical way for ‘excitation’ of the ice-rules configurational manifold. Compared to ices II and VIII, the induced hydrogen disorder in ice IX is smaller which suggests a higher density of configurational states close to the ground state. This study highlights the importance of dopants for exploring water’s phase diagram and underpins the highly complex solid-state chemistry of ice.

scholarly journals Observation of the Reversible Ice III to Ice IX Phase Transition by Using Ammonium Fluoride as Anti-Ice II Agent

2020 ◽  
Author(s):  
Christoph Salzmann ◽  
Zainab Sharif ◽  
Ben Slater ◽  
Craig L. Bull ◽  
Martin Hart
Keyword(s):  
Phase Transition ◽  
Thermal Expansion ◽  
Negative Thermal Expansion ◽  
Ammonium Fluoride ◽  
Torsional Strain ◽  
Lattice Constants ◽  
Helical Springs ◽  
Residual Hydrogen ◽  
Fluoride Doping ◽  
The Stability

Ice III is a hydrogen-disordered phase of ice that is stable between about 0.2 and 0.35 GPa. Upon cooling, it transforms to its hydrogen-ordered counterpart ice IX within the stability region of ice II. Because of this metastability, detailed studies of the ice III to ice IX phase transition have so far not been carried out. Using ammonium fluoride doping to prevent the formation of ice II, we now present a detailed study on this phase transition using in-situ powder neutron diffraction. The <i>a</i> and <i>c</i> lattice constants are found to expand and contract, respectively, upon hydrogen ordering yielding an overall negative volume change. Interestingly, the anisotropy in the lattice constants persists when ice IX is fully formed and negative thermal expansion is observed. Analogous to the isostructural keatite and <i>b</i>-spodumenes, the negative thermal expansion can be explained through the build-up of torsional strain within in the <i>a</i>-<i>b</i> plane as the helical ‘springs’ within the structure expand upon heating. The reversibility of the phase transition was demonstrated for the first time upon heating. The ammonium fluoride doping induces additional residual hydrogen disorder in ice IX and is suggested to be a chemical way for ‘excitation’ of the ice-rules configurational manifold. Compared to ices II and VIII, the induced hydrogen disorder in ice IX is smaller which suggests a higher density of configurational states close to the ground state. This study highlights the importance of dopants for exploring water’s phase diagram and underpins the highly complex solid-state chemistry of ice.

Synthesis of ZrW2O8 Ceramics and Composites from Aqueous Sol-Gel Precursors

2006 ◽  
Vol 45 ◽  
pp. 218-222
Author(s):  
Klaartje de Buysser ◽  
Serge Hoste ◽  
Isabel Van Driessche
Keyword(s):  
Phase Transition ◽  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Sol Gel ◽  
Negative Thermal Expansion ◽  
Oxide Mixture ◽  
Stability Range ◽  
Cubic Symmetry ◽  
Geometrical Effect

The thermal expansion of a ceramic material in general leads to a positive thermal expansion coefficient (α). In the last decennium, several families of materials which exhibit negative thermal expansion, arising from a specific geometrical effect in their so-called open framework structures, have been discovered. Usually, this negative thermal expansion coefficient is small, anisotropic and the phenomena occur in a very small temperature interval. ZrW2O8 is an exception because of its large and isotropic negative thermal expansion coefficient (NTE) in a temperature range from 0.5K to 1050K. A cubic symmetry is found over the entire stability range with a phase transition from α-ZrW2O8 to β-ZrW2O8 near 430K. This phase transition is noticed by a change in α. The aqueous citrate-gel method is a suitable synthesis route for negative thermal expansion ceramics and will give a fine, pure and homogenous oxide mixture, well suitable for the preparation of ZrW2O8. The expansion coefficient of α–ZrW2O8 is -11 μm/m K whereas for the β- ZrW2O8 a value of -3 is obtained.

Phase transition temperature and negative thermal expansion of Sc-substituted In2(MoO4)3 ceramics

2020 ◽  
Vol 55 (14) ◽  
pp. 5730-5740
Author(s):  
Zhiping Zhang ◽  
Yuenan Wang ◽  
Weikang Sun ◽  
Xiuyun Zhang ◽  
Hongfei Liu ◽  
...  
Keyword(s):  
Phase Transition ◽  
Thermal Expansion ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Negative Thermal Expansion

Thermal Cycling Effect on Mechanical Properties of Yttria-Stabilized Tetragonal Zirconia

2013 ◽  
Vol 538 ◽  
pp. 121-124
Author(s):  
Jing Zhang
Keyword(s):  
Mechanical Properties ◽  
Phase Transition ◽  
Thermal Expansion ◽  
Flexural Strength ◽  
Thermal Cycling ◽  
Tetragonal Zirconia ◽  
Yttria Stabilized Zirconia ◽  
Stabilized Zirconia ◽  
Optical Applications ◽  
The Stability

Yttria-stabilized zirconia (YSZ) is an important material in the area of energy and optical applications. In this study, the mechanical properties (Young’s modulus, Vickers hardness, flexural strength, and coefficient thermal expansion) and physical properties (phase transition) of yttria-stabilized tetragonal zirconia polycrystalline (Y-TZP) was reported. The effect of thermal cycling on the mechanical properties and the stability was also evaluated.

ChemInform Abstract: Phase Transition and Negative Thermal Expansion in Orthorhombic Dy2W3O12.

ChemInform ◽  
2016 ◽  
Vol 47 (52) ◽  
Author(s):  
Weigang Cao ◽  
Qiang Li ◽  
Kun Lin ◽  
Zhanning Liu ◽  
Jinxia Deng ◽  
...  
Keyword(s):  
Phase Transition ◽  
Thermal Expansion ◽  
Negative Thermal Expansion

Structure, phase transition and negative thermal expansion in ammoniated ZrW2O8

2016 ◽  
Vol 3 (6) ◽  
pp. 856-860 ◽  
Author(s):  
Weigang Cao ◽  
Qingzhen Huang ◽  
Yangchun Rong ◽  
You Wang ◽  
Jinxia Deng ◽  
...  
Keyword(s):  
Phase Transition ◽  
Thermal Expansion ◽  
Structural Changes ◽  
Negative Thermal Expansion ◽  
Structure Phase ◽  
Structure Phase Transition

The local structural changes of ZrW2O8 after ammoniation treatment.

scholarly journals Study of Negative Thermal Expansion and Shift in Phase Transition Temperature in Ti4+- and Sn4+-Substituted ZrW2O8Materials

2008 ◽  
Vol 47 (2) ◽  
pp. 736-741 ◽  
Author(s):  
Klaartje De Buysser ◽  
Isabel Van Driessche ◽  
Bart Vande Putte ◽  
Paul Vanhee ◽  
Joseph Schaubroeck ◽  
...  
Keyword(s):  
Phase Transition ◽  
Thermal Expansion ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Negative Thermal Expansion

Polymorphism in Ho2(MoO4)3

2013 ◽  
Vol 28 (S2) ◽  
pp. S33-S40 ◽  
Author(s):  
C. González-Silgo ◽  
C. Guzmán-Afonso ◽  
V. M. Sánchez-Fajardo ◽  
S. Acosta-Gutiérrez ◽  
A. Sánchez-Soares ◽  
...  
Keyword(s):  
Phase Transition ◽  
Thermal Expansion ◽  
Room Temperature ◽  
Linear Expansion ◽  
Negative Thermal Expansion ◽  
Thermal Treatments ◽  
Positive Coefficient ◽  
X Ray ◽  
Expansion Coefficients ◽  
First Time

Two polymorphs of Holmium molybdate, known as β'-phase and γ-phase, were prepared by solid state reaction with different thermal treatments. These polycrystalline samples have been studied for the first time by X-ray thermodiffractometry from room temperature up to 1300 K. We found that the initial β'-phase undergoes a transition to a β-phase and then to a γ-phase. The γ (hydrated)-phase, turns to the γ (dehydrated)-phase and then to the β-phase. Each sequence involves a reversible and an irreversible phase transition for Ho2(MoO4)3. Both polymorphs have remarkable physical properties like nonlinear optics, ferroelectricity and negative thermal expansion. We have calculated the linear expansion coefficients of both phases. We have obtained a positive coefficient for the β'-phase and a negative one for the γ-phase. Moreover, we have made a comparison of the obtained coefficients with previous results for other rare earth molybdates.

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